With “Obvious Child,” her 2014 feature writing/directing debut, Gillian Robespierre achieved the near impossible, delivering a bittersweet comedy/drama about a young woman who opts for an abortion.

Her sophomore effort, “Landline,” is equally ambitious, if not quite so successful.

The topic here is infidelity and its repercussions. There’s some angst tossed around, yes, but this mostly low-keyed comedy keeps its eye on notion that sometimes marital trauma ends up being better for everyone. (Robespierre has said in interviews that both she and co-writer Elizabeth Holm saw their parents’ marriages break up because of adultery…but that in the long run everyone was better off for it.)

Set in the pre-cell phone ’90s, the film centers on the four members of the Quinn family in New York City.

Father Alan (John Turturro) is a advertising copywriter who really wants to turn out great poetry and prose. Mother Pat (Edie Falco) has her hands full with their 17-year-old daughter Ali (Abby Quinn), a bad-tempered rebel specializing in ditching classes, smoking dope and experimenting with sex.

Their oldest daughter, Dana (Jenny Slade, star of “Obvious Child”), has already moved out and is living with her fiancé. She seems to be as straight and uptight as Ali is angry and adventurous; when uncomfortable Dana erupts in helium giggles. Concerned that her life’s turning into a long slog, she suggests to fiance Ben (Jay Duplass) that they have sex during a hike in the woods. All they get for the effort is a bad case of poison ivy.